In the packaging of integrated circuits, semiconductor dies may be stacked through bonding, and may be bonded to other package components such as interposers. The resulting packages are known as Three-Dimensional Integrated Circuits (3DICs). The heat dissipation is a challenge in the 3DICs. There exists a bottleneck regarding how to efficiently dissipate the heat generated in the inner dies of the 3DICs. The heat generated in the inner dies has to be dissipated to outer dies before it can be conducted to any heat spreader. Between the stacked dies, however, there exist other materials such as underfill, molding compound, etc, which are not effective in conducting heat.
The solutions for improving the heat dissipation are being developed. For example, micro-channels may be built inside silicon substrates for heat dissipation. Although the micro-channels may be filled with materials or fluids having a good thermal conductivity to improve the overall heat dissipation efficiency of the resulting device die, the manufacturing cost and time-to-market of the device dies became an issue.